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https://issues.apache.org/jira/browse/XALANC-733?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13464742#comment-13464742
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Martin Elzen commented on XALANC-733:
-------------------------------------
Okay, well, IBM is telling you a part of the story... but not all of it. They
failed to mention that the "const int Test::N;" bit needs to be in a .cpp file.
If you put in in the header instead you mess up what IIRC they call C++'s
seperate compilation model. If you then happen to include the same header file
into 2 different translation units, those two translation units can't be
combined since they contain a duplicate definition.
Here's a "mored-together" file (if you want to use it esp. the makefile you
will need to put the tabs where they belong!)
::::::::::::::
test.h
::::::::::::::
#if !defined(TEST_HDR)
#define TEST_HDR
class Test
{
public:
static const int N = 10;
void sayHi() const;
};
#if defined(BAD)
const int Test::N;
#endif
#endif
::::::::::::::
test.cpp
::::::::::::::
#include "test.h"
#include <iostream>
#if defined(GOOD)
const int Test::N;
#endif
void Test::sayHi() const
{
std::cout << "Test says 'Hi'.\n";
}
::::::::::::::
testUserOne.h
::::::::::::::
class UserOne {
public:
void sayHi() const;
};
::::::::::::::
testUserTwo.h
::::::::::::::
class UserTwo {
public:
void sayHi() const;
};
::::::::::::::
testUserOne.cpp
::::::::::::::
#include "test.h"
#include "testUserOne.h"
#include <iostream>
void UserOne::sayHi() const
{
std::cout << "UserOne, Test::N == " << Test::N << "\n";
}
::::::::::::::
testUserTwo.cpp
::::::::::::::
#include "test.h"
#include "testUserTwo.h"
#include <iostream>
void UserTwo::sayHi() const
{
std::cout << "UserTwo, Test::N == " << Test::N << "\n";
}
::::::::::::::
main.cpp
::::::::::::::
#include "test.h"
#include "testUserOne.h"
#include "testUserTwo.h"
#include <iostream>
int main(int argc, const char *argv[] )
{
std::cout << "at start of main\n";
Test tst;
UserOne one;
UserTwo two;
tst.sayHi();
one.sayHi();
two.sayHi();
std::cout << "at end of main\n";
return 0;
}
::::::::::::::
makefile
::::::::::::::
CC=g++
#OPTIONS=-DBAD
OPTIONS=-DGOOD
clean:
rm main main.o test.o testUserOne.o testUserTwo.o
test.o: test.h test.cpp
$(CC) $(OPTIONS) -o test.o -c test.cpp
testUserOne.o: test.h testUserOne.h testUserOne.cpp
$(CC) $(OPTIONS) -o testUserOne.o -c testUserOne.cpp
testUserTwo.o: test.h testUserTwo.h testUserTwo.cpp
$(CC) $(OPTIONS) -o testUserTwo.o -c testUserTwo.cpp
main.o: main.cpp
$(CC) $(OPTIONS) -o main.o -c main.cpp
main: test.o testUserOne.o testUserTwo.o main.o
$(CC) $(OPTIONS) -o main test.o testUserOne.o testUserTwo.o main.o
#####
GNU g++ (4.4) won't compile this when the BAD define in the Makefile isn't
commented-out, while it will compile and link just fine when the GOOD define
isn't commented out.
That's why I'm pushing for an approach using a static inline member function
that returns a reference to a static object that is constructed within said
static function. First of all, this is a well-known idiom (it's the singelton
design pattern). You are also making the language work for you: doing it like
this makes it C++'s responsibility to create the object exactly once. And as a
plus point, this kind of design will even be more thread-safe when C++
compilers more completely support the C++11 standard.
> Ensure that XalanLocator::getSystemId() and getPublicId() do not return NULL
> ----------------------------------------------------------------------------
>
> Key: XALANC-733
> URL: https://issues.apache.org/jira/browse/XALANC-733
> Project: XalanC
> Issue Type: Bug
> Components: XalanC, XPathC
> Affects Versions: 1.11
> Reporter: Steven J. Hathaway
> Assignee: Steven J. Hathaway
> Attachments: XalanLocator-3.patch, XalanLocator.patch,
> XalanLocator.patch2
>
>
> The recommended patch to "xalanc/PlatformSupport/XalanLocator.hpp"
> ensures that getSystemId() and getPublicId() do not return NULL pointers.
> XalanC source files that can benefit from the patch include:
> xalanc/PlatformSupport/ProblemListenerBase.cpp
> xalanc/PlatformSupport/XSLException.cpp
> xalanc/XPath/XPathExecutionContextDefault.cpp
> The patch will be submitted shortly.
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